Increasingly, Internet Protocol/Multiprotocol Label Switching (IP/MPLS) networks must be able to support high availability services such as voice transmission. In order to meet this requirement on their own, IP/MPLS networks, comprising a packet network and an underlying optical network, must be able to achieve the level of reliability and maintenance traditionally available in transport networks. One aspect of providing this reliability is deciding in which network packet link protection should be implemented.
In response to this dilemma, protection mechanisms operating in the packet network such as MPLS fast reroute have been designed that can protect services in time frames equivalent to Synchronous optical Networks (SONET) automatic protection switching once a failure has been detected. Like any other similar scheme, MPLS fast reroute is required to maintain additional protection-specific bandwidth.
In parallel to advances developed in the protection of packet networks, optical networks have also evolved to support new types of architectures and protection schemes. These schemes, such as mesh protection, have been designed to be more flexible and efficient.
The development of improved protection methods in both optical networks and packet networks has created an opportunity for service and network engineers to choose how to best implement packet link protection.
When trying to decide how and where to implement packet link protection in a packet transport network, one criterion worth examining is the bandwidth requirement of each method of protection.
If packet link protection is completely handled by the packet network, no protection is required in the optical network. Therefore the packet network can use an unprotected optical connection service. If a packet link is protected by the optical network, then MPLS fast reroute or an alternative protection scheme is not required in the packet network. Using the full complement of both MPLS fast reroute and optical mesh protection results in a waste of resources.